Expandable pipe including a liner for restoring a conduit

ABSTRACT

An expandable pipe for restoring a damaged pipe is provided. The expandable pipe includes a liner formed of thermoplastic polyurethane, and grout material applied to the exterior surface of the liner. The exterior surface includes a plurality of flared tips and grooves, and each groove is located between adjacent flared tips. The grout material is disposed on the flared tips and in the grooves of the liner. The method used to restore the damaged pipe includes clamping the liner with the grout material on a puller-sealer fixture having a U-shaped cross-section to prevent debris from entering the interior of the liner, and pulling the puller-sealer fixture and liner through the damaged pipe. The grout material expands in volume upon exposure to moisture, ultra violet radiation, heat, and/or ultrasonics, and fills cracks or other imperfections and voids along the interior surface of the conduit, caused by corrosion, erosion, or other circumstances.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. Divisional patent application claims priority to U.S. utility patent application Ser. No. 15/419,525, filed Jan. 30, 2017, which claims priority to U.S. provisional patent application No. 62/289,760, filed Feb. 1, 2016, and U.S. provisional patent application No. 62/432,265, filed Dec. 9, 2016, the contents of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to products and methods for restoration of damaged conduits.

2. Related Art

Grout materials are often used to repair an interior surface of corroded, cracked, or otherwise damaged conduit. One method of repairing a metal conduit includes coupling short links of stainless steel sleeves to one another to form a liner, and pulling the stainless steel liner through the metal conduit with a cable to present a small annular space between the stainless steel liner and the metal conduit. A grout material is then pumped into the annular space to fill the annular space and cracks in the metal conduit. However, this method includes significant material costs and labor costs. Further, in the above method and other methods currently used, controlling the placement of the grout material is difficult. Oftentimes, the grout material is disposed unevenly along the damaged conduit and does not fill all of the cracks of the conduit.

Another more recently developed method for repairing damaged conduits with a grout material includes the use of an expandable pipe. The expandable pipe includes a liner and the grout material disposed in grooves along the exterior surface of the liner. The liner with the grout material is disposed in an opening of the damaged conduit, and then exposed to moisture such that the grout material expands and engages the interior surface of the damaged conduit.

The grooves of the liner allow for the expandable pipe to fold for convenient transportation of the expandable pipe. The grooves also provide flexibility for maneuvering the expandable pipe around bends of the damaged conduit. The grooves of the liner also allow for controlled placement and amount of the grout material along the exterior surface of the liner. The grooves maintain the placement of the grout material as the liner is disposed in the damaged conduit. The grout material expands to engage the interior surface of the damaged conduit and fills cracks, holes, indentations, or other imperfections and voids along the interior surface of the conduit, caused by corrosion, erosion, or other circumstances. In other words, the expandable pipe relines the interior surface of the damaged conduit. The expandable pipe also provides a seal to the conduit and prevents water and debris from entering the conduit. The grout material of the expandable pipe can also expand through holes in the conduit and fill voids in earth surrounding the conduit. The expandable pipe is a cost-effective and convenient way to repair and restore conduits of various types, such as sewer pipes, potable water pipes, electrical pipes, and air ducts. An example of the expandable pipe is disposed in U.S. Pat. No. 7,942,167.

SUMMARY

One aspect of the invention provides an expandable pipe for restoring a damaged pipe. The expandable pipe includes a liner formed of a thermoplastic polyurethane and presenting an exterior surface. The exterior surface of the liner includes a plurality of flared tips and grooves, and each groove is located between adjacent flared tips. A grout material is disposed on the flared tips and in the grooves of the liner. The grout material is expandable in a dimension upon exposure to moisture, ultra violet radiation, heat, and/or ultrasonics.

According to another embodiment, the expandable pipe includes a liner formed of a polymer-based and/or elastomer-based material, and the liner includes a plurality of fibers. The liner includes an exterior surface, and the exterior surface of the liner includes a plurality of grooves. A grout material is disposed in the grooves of the liner, and the grout material is expandable in a dimension upon exposure to moisture, ultra violet radiation, heat, and/or ultrasonics.

Another aspect of the invention provides a method of manufacturing an expandable pipe for restoring a damaged pipe. The method includes extruding a liner from a thermoplastic polyurethane, wherein the extruded liner includes an exterior surface with a plurality of flared tips and grooves, each groove being located between adjacent flared tips. The method further includes disposing a grout material on the flared tips and in the grooves of the liner, wherein the grout material is expandable in a dimension upon exposure to moisture, ultra violet radiation, heat, and/or ultrasonics.

According to another embodiment, the method of manufacturing the expandable pipe for restoring a damaged pipe comprises extruding a liner formed of a polymer-based and/or elastomer-based material and including a plurality of fibers, wherein the extruded liner include an exterior surface with a plurality of grooves. The method further includes disposing a grout material in the grooves of the liner, wherein the grout material is expandable in a dimension upon exposure to moisture, ultra violet radiation, heat, and/or ultrasonics.

Yet another aspect of the invention provides a method of restoring a damaged pipe. The method includes providing a liner formed of a polymer-based and/or elastomer-based material, the liner including an exterior surface, and applying a grout material to the exterior surface of the liner. The method further includes disposing the liner on a puller-sealer fixture having a U-shaped cross-section, and pulling the puller-sealer fixture and liner with the grout material through the damaged pipe. The method further includes exposing the grout material on the exterior surface of the liner to moisture, ultra violet radiation, heat, and/or ultrasonics, the exposing step causing the grout material to expand and contact an inner diameter surface of the damaged pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a cross-sectional view of a portion of a liner according to an example embodiment of the invention;

FIG. 2 is a cross-sectional view of the entire liner disposed inside of a host pipe according to the example embodiment of the invention;

FIG. 3 is a cross-sectional view of a puller/sealer fixture disposed inside of the host pipe which configures the liner for passage through the host pipe with minimal interference with the inner diameter of the host pipe and which seals an inner diameter of the liner from water, debris, and grout material;

FIG. 4 illustrates the puller/sealer fixture attached to a spraying fixture and rolling dolly used to install the liner in the host pipe;

FIG. 5 illustrates an example of a dip tank assembly for coating the liner with a 1-part moisture-curing urethane grout according to an example embodiment; and

FIG. 6 includes example specifications of a coating tank and a mixing tank of the dip tank assembly according to the example embodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

An expandable pipe 20 for restoring a damaged conduit 22, also referred to as a host pipe, is shown in FIGS. 1-13 of the related U.S. provisional patent application No. 62/289,760. The damaged conduit or host pipe 22 is a pipe in the ground that requires rehabilitation. For example, the expandable pipe 20 can be used to repair or restore conduits or host pipe 22 of various types, such as water conduits, gas conduits, oil conduits, sewer pipes, potable water pipes, electrical pipes, and air ducts.

The expandable pipe 20 includes an improved liner 24 formed of a polymer-based and/or elastomer-based material, and a grout material 30 applied to an exterior surface 26 of the liner 24. The exterior surface 26 of the liner 24 can include grooves 28 or a profiled surface to maintain the grout material 30 in place as the liner 24 is disposed in the host pipe 22. The grout material 30 expands in a dimension D₁, such as volume, upon exposure to or contact with moisture, ultra violet (UV) radiation heat, and/or ultrasonics. Moisture, ultra violet radiation, heat, and/or ultrasonics are also able to cure the grout material 30. Thus, after such exposure, the grout material 30 contacts an inner diameter surface of the damaged host pipe 22 and fills voids in the damaged host pipe 22. The volume of the grout material 30 after expansion is 1% to 1000% greater than the volume of the grout material 30 before expansion. The grout material 30 then hardens to restore the integrity of the host pipe 22. In addition to the embodiments described in U.S. provisional patent application No. 62/289,760, several other embodiments are possible, which are described herein with reference to FIGS. 1-4 of the present application.

As stated above, the liner 24 is formed of a polymer-based and/or elastomer-based material. The liner 24 can be formed of a single polymer-based or elastomer-based material, for example a thermoplastic material. Alternatively, the liner 24 can include more than one polymer and/or elastomer. According to example embodiments, the liner 24 is extruded from clear thermoplastic polyurethane (TPU). The clear liner 24 is preferred for viewing purposes, for example to view the inside of the damaged host pipe 22 being repaired using a video camera. However, the liner 24 could be another color and does not have to be clear to function as intended. The liner 24 could also have another composition. For example, the liner 24 could be formed of any material that can be folded then expanded, not limited to TPU. For example, the liner 24 could be formed of polyethylene or any medium density plastic. The liner 24 can optionally include fibers in the polymer-based and/or elastomer-based material, at least in a thin base portion of the liner 24, to increase strength and prevent ballooning of the liner 24. For example, the liner 24 could include a composite of multiple polymers and/or elastomers, and reinforcing fibers. The visual clarity of the TPU allows for convenient video identification of lateral access points to allow for trimming of the liner 24. After installation of the liner 24 in the host pipe 22, an interior diameter surface 32 of the liner 24 located opposite the exterior surface 26 is smooth.

According to a preferred embodiment, the grooves 28 of the liner 24 are achieved by a profile on an exterior surface 26, also referred to as an outer diameter surface, of the liner 24, as shown in FIGS. 1 and 2. In the embodiment of FIGS. 1 and 2, the profile of the exterior surface 26 of the liner 24 includes flared tips 34 which act as a mechanical lock for the grout material 30 applied to the exterior surface 26 of the liner 24. FIG. 1 only shows the flared tips 34 along a portion of the exterior surface 26 of the liner 24, but the flared tips 34 are preferably located along the entire exterior surface 26 of the liner 24, and continuously around the outer circumference of the liner 24. In the example of FIGS. 1 and 2, each groove 28 is formed between two adjacent flared tips 34, and the grout material 30 is contained in those grooves 28. The flared tips 34 include a stem 36 extending perpendicular to the base of the liner 24, and an enlarged top 38 which flares outwardly relative to the stem 36. The diameter or width of the enlarged top 38 is greater than the diameter or width of the stem 36. The flared tips 34 shown in FIGS. 1 and 2 are only an example, as the shape and dimensions of the flared tips 34 can vary. Alternatively, other profiled shapes and dimensions can be used to achieve the grooves 28 in the liner 24. However, the flared tips 34 or other mechanical locking features are not required if a sufficient bond between the liner 24 and the grout material 30 is achieved.

The liner 24 can be formed by extrusion, preferably in a flat extrusion die to produce a flat product, such as a sheet of the TPU or another thermoplastic material. The flat extruded product is then welded into a circular pipe shape to produce the liner 24 and so as to reside inside the host pipe 22, as shown in FIG. 2. In other words, the flat product is welded it at a circumference that matches the required diameter for the liner 24. The diameter of the liner 24 should be less than the inner diameter of the host pipe 22 when the liner 24 is inflated. For example, the liner 24 of the example embodiment has a 7.5 inch inner diameter when inflated, and the host pipe 22 has an 8 inch inner diameter. The liner 24 could be extruded to size, as a circular tube, however certain raw materials are difficult to extrude into circular geometries due to a lack of melt strength. The other advantage of extruding flat and welding is the ability to obtain any diameter with limited tooling.

According to the example embodiments, during installation of the liner 24 in the host pipe 22, the grout material 30, preferably urethane grout, such as an unactivated liquid polyurethane, is applied to the exterior surface 26 of the liner 24. The grout material 30 can optionally include fibers to increase strength. At this point, the liner 24 is folded flat for installation. Before the liner 24 enters the host pipe 22, it is coated on the exterior surface 26 with 1-part moisture-curing urethane grout. This grout material 30 cures and expands during installation, adhering to both the TPU liner 24 and the host pipe 22.

As will be discussed further below, in the example embodiments, a 2-part urethane grout is sprayed onto the inner diameter surface of the host pipe 22 during installation. In other words, urethane grout is sprayed onto the inner diameter surface of the host pipe 22 during installation, and as the TPU liner 24 is being pulled through the host pipe 22 by a cable 40 and a rolling dolly 42, a set of mixing/spraying heads 44 mounted to the rolling dolly 42 sprays the coating of 2-part urethane grout (optionally including entrained fibers) onto the inner diameter surface of the host pipe 22 (just ahead of the liner 24 as it is pulled through the host pipe 22). The 2-part urethane grout includes 1-part of the urethane and 1-part of a curing agent. The 1-part expanding urethane grout applied to the exterior surface 26 of the liner 24 before it enters the host pipe 22 combined with the 2-part expanding urethane grout sprayed onto the inner diameter surface of the host pipe 22 as the liner 24 is pulled through the host pipe 22, serve to provide a high strength, and highly adhesive interface between the liner 24 and the host pipe 22, while also migrating and expanding to fill any cracks, voids or imperfections in the host pipe 22 or adjoining service lines.

The method of installing the liner 24 in the host pipe 22 according to example embodiments will now be described in more detail with reference to FIGS. 3 and 4. When the TPU liner 24 is ready for installation, it is coiled, laying flat like a fire hose, onto reels. At the jobsite where the host pipe 22 is located, the liner 24 is routed through a dip (or soaking) tank assembly 56 containing the 1-part moisture-curing urethane grout. FIG. 5 illustrates the liner 24 being routed through the dip tank assembly 56 according an example embodiment. The dip tank assembly 56 is capable of uniformly coating the liner 24 with the 1-part moisture-curing urethane grout, for example an unactivated liquid polyurethane. The dip tank assembly 56 is also able to apply the 1-part moisture-curing urethane grout to liners 24 varying from 2 inches to 20 feet in diameter, for example 6 inches to 12 inches in diameter. The dip tank assembly 56 is robust in construction, easy to maintain and service, and is portable in nature. As shown in FIG. 5, the dip tank assembly 56 includes a coating tank 58 which guides the liner 24 through the liquid polyurethane using a series of vertical and horizontal rollers 60. Guide rollers G are used to guide the liner 24 from a supply into the coating tank 58, and guide rollers G are again used to guide the coated liner 24 from the coating tank 58 to a manhole where the liner 24 will be used to repair the damaged pipe 22. The coating tank 58 is typically formed of aluminum and includes a removable top 62 and a drain 64. However, the design and the material used to form the coating tank 58 can vary. The rollers 60 are typically formed of ultra-high density polyurethane. However, the dip tank assembly 56 could include a different array of rollers 60, and/or the rollers 60 could be formed of different materials. The dip tank assembly 56 also includes a mixing tank 66 acting as a reservoir to supply additional liquid polyurethane to the coating tank 58 on demand to maintain the liquid level in the coating tank 58. The mixing tank 66 can also be formed of aluminum, or another material. Example specifications of the coating tank 58 and the mixing tank 66 are provided in FIG. 6. These specifications are general in nature and can be adjusted as required prior to fabrication of the dip tank assembly 56.

The TPU liner 24, with its exterior surface 26 soaked in the urethane grout, is directed down into an opening of the host pipe 22. The TPU liner 24 is there attached to a spraying fixture 46 via the puller/sealer fixture 48, as shown in FIGS. 3 and 4. The puller/sealer fixture 48 is a solid piece of material which serves as a mounting fixture which configures the liner 24 for optimal passage through the host pipe 22, with minimal interference with the inner diameter surface of the host pipe 22. In the example embodiment, the puller/sealer fixture 48 has a U-shaped cross-section with no sharp edges. The puller/sealer fixture 48 maintains the liner 24 in an appropriate position, without any sharp edges along the liner 24. In the example embodiment, the puller/sealer fixture 48 has an outer perimeter of 23.560 inches, which is equal to the length of the 7.5 inch inner diameter of the liner 24. Jigs or clamps 50 can be used to secure the liner 24 to the puller/sealer fixture 48. The puller/sealer fixture 48 also prevents debris, moisture, and/or the grout material 30 from entering the interior of the liner 24. For example, the clamps 50 can secure the liner 24 tightly against the puller/sealer fixture 48 to prevent the debris, moisture, and/or the grout material 30 from entering the interior of the liner 24. During installation, the puller/sealer fixture 48 is attached to the rolling dolly 42 and pulled by the cable 40 through the host pipe 22.

A set of the mixing/spraying heads 44 is also attached to the dolly 42 and are pulled through the host pipe 22 during installation. The mixing/spraying heads 44 receive two urethane grout feed lines 52, 54 routed from the pulling side, such as along the cable, that will mix the 2-part grout before spraying the mixture onto the inner diameter surface of the host pipe 22. One feed line 52 includes the urethane and a second feed line 54 includes a curing agent. The rate of flow into the mixing/spraying heads 44 will be controlled automatically as a function of the velocity of the dolly 42 and the entire assembly through the host pipe 22 so as to assure a consistent coating of the host pipe 22 throughout. Thus, the area between the liner 24 and the host pipe 22 is filled with both the 1-part and 2-part urethane grout. Once the full length of the TPU liner 24 has been pulled through the host pipe 22, the ends of the liner 24 are capped, and the liner 24 is inflated to a specific pressure. The grout material 30 is exposed to moisture, ultra violet radiation, heat, and/or ultrasonics and thus cures and expands to adhere to the liner 24 and the inner diameter surface of the damaged pipe 22. The grout material 30 is typically in the form of a foam and bonds to the extruded liner 24, forming an adhesive and preferably cohesive bond, such that the plurality of flared tips 34 are not required for the liner 24 and grout material to maintain contact. After an appropriate curing period, pressure is released from the interior of the liner 24. Ends of the liner 24, as well as access points for laterals (service lines), can then be trimmed.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the following claims. 

The invention claimed is:
 1. A method of restoring a damaged pipe, comprising the steps of: providing a liner formed of a polymer-based and/or elastomer-based material, the liner including an exterior surface, applying a grout material to the exterior surface of the liner, disposing the liner on a puller-sealer fixture having a U-shaped cross-section, pulling the puller-sealer fixture and liner with the grout material through the damaged pipe, and exposing the grout material on the exterior surface of the liner to moisture, ultra violet radiation, heat, and/or ultrasonics, the exposing step causing the grout material to expand and contact an inner diameter surface of the damaged pipe.
 2. The method of claim 1, wherein the cross-section of the puller/sealer fixture includes no sharp edges, and the puller/sealer fixture maintains the liner in position while pulling the liner through the damaged pipe.
 3. The method of claim 1, wherein the exterior surface of the liner includes a plurality of flared tips and grooves, each groove is located between adjacent flared tips, each of the flared tips of the liner includes a stem extending perpendicular to a base of the liner and an enlarged top flaring outwardly relative to the stem, the enlarged top has a width greater than a width of the stem.
 4. The method of claim 1, wherein the step of pulling the puller-sealer fixture and liner with the grout material through the damaged pipe includes pulling the puller-seal fixture attached to a rolling dolly by a cable.
 5. The method of claim 1, wherein the liner is secured to the puller/sealer fixture by clamps which prevent debris, moisture, and/or the grout material from entering an interior of the liner.
 6. The method of claim 1, wherein the step of applying the grout material to the exterior surface of the liner includes applying unactivated liquid polyurethane grout to the exterior surface, the grout material further includes a 2-part urethane grout, and further including the step of spraying the 2-part urethane grout onto the inner diameter surface of the damaged pipe while pulling the puller-sealer fixture and liner through the damaged pipe, the 2-part urethane grout including urethane and a curing agent.
 7. The method of claim 6, wherein the step of pulling the puller-sealer fixture and liner with the grout material through the damaged pipe includes pulling the puller-seal fixture attached to a rolling dolly by a cable, and the spraying step includes spraying the 2-part urethane grout through spraying heads attached to the rolling dolly ahead of the liner, the spraying heads receive two feed lines routed along the cable, one of the feed lines includes the urethane and the other feed line includes the curing agent.
 8. The method of claim 1, wherein the step of applying the grout material to the exterior surface of the liner includes applying unactivated liquid polyurethane grout to the exterior surface of the liner includes by routing the liner through a dip tank assembly containing the grout material.
 9. The method of claim 1 including exposing the grout material to moisture, ultra violet radiation, heat, and/or ultrasonics such that the grout material expands 1% to 1000% in volume, cures, and adheres to the liner and the inner diameter surface of the damaged pipe.
 10. The method of claim 1, wherein the step of providing the liner includes extruding a flat sheet of the polymer-based and/or elastomer-based material, and welding the flat sheet to form the liner.
 11. The method of claim 1, wherein the step of providing the liner includes extruding the liner from thermoplastic polyurethane including fibers, the thermoplastic polyurethane is clear, the exterior surface of the liner includes a plurality of flared tips and grooves, each groove is located between adjacent flared tips, the flared tips are located along an entirety of the exterior surface of the liner and continuously around an outer circumference of the liner, each of the flared tips of the liner includes a stem extending perpendicular to a base of the liner and an enlarged top flaring outwardly relative to the stem, the enlarged top has a width greater than a width of the stem, the step of extruding the liner is performed by an extrusion die which produces a flat sheet of the thermoplastic polyurethane including fibers, the step of providing the liner further includes welding the flat sheet to produce the liner, the liner has a diameter which is less than a diameter of the inner diameter surface of the damaged pipe when the liner is inflated, the liner has a diameter of 6 inches to 12 inches when the liner is inflated, the cross-section of the puller/sealer fixture includes no sharp edges, the puller/sealer fixture maintains the liner in position while pulling the liner through the damaged pipe, the step of applying the grout material to the exterior surface of the liner includes disposing unactivated liquid polyurethane grout on the flared tips and in the grooves, the flared tips and grooves maintain the unactivated liquid polyurethane grout on the exterior surface of the liner during the step of pulling the liner through the damaged pipe, the unactivated liquid polyurethane grout includes fibers and expands 1% to 1000% in volume upon exposing the grout material to moisture, the step of disposing the unactivated liquid polyurethane grout on the flared tips and in the grooves includes applying the unactivated liquid polyurethane grout to the exterior surface of the liner when the liner is flat, the unactivated liquid polyurethane grout is cured by moisture, the step of disposing the unactivated liquid polyurethane grout on the flared tips and in the grooves includes routing the liner through a dip tank assembly containing the unactivated liquid polyurethane grout, the dip tank assembly includes a coating tank which guides the liner through the unactivated liquid polyurethane grout using a series of rollers formed of ultra-high density polyurethane, the coating tank is formed of aluminum and includes a removable top and a drain, the dip tank assembly further includes a mixing tank formed of aluminum providing a reservoir of the unactivated liquid polyurethane grout and supplying the unactivated liquid polyurethane grout to the coating tank, the step of pulling the puller-sealer fixture and liner with the grout material through the damaged pipe includes pulling the puller-seal fixture attached to a rolling dolly by a cable, the puller/sealer fixture is a solid piece of material and is free of sharp edges along the liner, the liner is secured to the puller/sealer fixture by clamps which prevent debris, moisture, and/or the grout material from entering an interior of the liner, and further including spraying a 2-part urethane grout onto the inner diameter surface of the damaged pipe while pulling the puller-sealer fixture and liner through the damaged pipe, the 2-part urethane grout including urethane and a curing agent, the spraying step including spraying the 2-part urethane grout through spraying heads attached to the rolling dolly ahead of the liner, the spraying heads receive two feed lines routed along the cable, one of the feed lines includes the urethane and the other feed line includes the curing agent, mixing the urethane and the curing agent before spraying the 2-part urethane grout on the inner diameter surface of the damaged pipe, the grout material includes a mixture of the unactivated liquid polyurethane grout on the exterior surface of the liner and the 2-part urethane grout on the inner diameter surface of the damaged pipe, and further including the steps of capping ends of the liner and inflating the liner to a specific pressure after spraying the 2-part urethane grout on the inner diameter surface of the damaged pipe, the exposing step including exposing the grout material to moisture such that the grout material expands 1% to 1000% in volume, cures, and adheres to the liner and the inner diameter surface of the damaged pipe, and releasing the pressure from the inflated liner after the grout material is cured.
 12. The method of claim 1, wherein the step of providing the liner includes extruding the liner from a thermoplastic material, the grout material applied to the exterior surface of the liner is in the form of a foam, and the grout material forms an adhesive or cohesive bond with the extruded liner such that a plurality of flared tips on the exterior surface of the extruded liner are not required for the liner and the grout material to maintain contact. 